A major threat to human health is cancer, and worldwide at least 5 million people die from cancer annually. Most cancers in humans are caused by environmental factors. Although certain methods of cancer treatment are available, such as surgery, radiotherapy, and chemotherapy, the rate of success is still quite limited. Among available methods of treatment, chemotherapy is one of the most effective.
One category of cancer chemotherapy agents are the inhibitors or antagonists of both receptor tyrosine kinases and non-receptor tyrosine kinases. Specific targets include VEGFR, EGFR, HER2, SRC, JAK and TEK.
Certain thieno-pyridazine compounds have been found to have anti-tumor activities. For example, WO2005105808 discloses such a compound as an IKK inhibitor:
WO2007124181 discloses compounds that are inhibitors of p38 protease, a type of tyrosine kinase:
Further, WO 03029241, WO 03028731 and WO2005066163 disclose similar compounds that are inhibitors of CHK1.
Nevertheless, there is a need for more anti-cancer compounds that are inhibitors of tyrosine kinases, especially CHK1/CHK2.